Chapter 6 and 7
Meiosis and Mendel
Extending Mendelian Genetics
Warm up (2-23-16)
Explain what you remember from middle school
about genetics
(Think about phenotype and genotype, think
about Punnett Squares, think about Mendel,
and gene inheritance.)
Outline
• Objectives
• Chromosomes and Meiosis
• Review genetics and what was discussed in
middle school
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the number of
chromosomes present in sex cells versus
somatic cells.
Warm up (2-24-16)
Explain the difference between diploid and
haploid and what those terms mean.
Outline
• Objectives
• Make a baby worksheet
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the number of
chromosomes present in sex cells versus
somatic cells.
Make a baby worksheet
• Pick a partner and walk your way through the
worksheet.
• This will give us an introduction to genetics
and how gene inheritance works.
Warm up (2-25-16)
How many cells go into the process of meiosis?
How many cells come out of the process of
meiosis?
Please explain how many chromosomes are in
the cells going into meiosis and how many
chromosomes are in the cells coming out of
meiosis.
Outline
• Objectives
• Process of Meiosis notes
• Meiosis Drawings
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
Warm up (2-26-16)
What are the phases of meiosis? Please be
specific and indicate which division those phases
are associated with.
Outline
• Objectives
• Finish Meiosis notes
• 6.1 and 6.2 section review questions
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
Warm up (2-29-16)
Explain what genetics is and how specific traits
can be determined for organisms.
Outline
•
•
•
•
•
Objectives
Read 6.3 Mendel and Genetics
Heredity
video
Mendel and Heredity
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
6.1 Notes
• Gametes have half the number of
chromosomes that body cells have
– There are body cells and gametes
• Somatic cells: body cells, make up most of your body
tissues and organs
• Gametes: sex cells, egg in the female and sperm in the
male
Your body cells have autosomes and
sex chromosomes
– Homologous chromosomes: 2 chromosomes
• “having the same structure”
• One from mother, one from father
• Have copies of the same genes although the copies may
be different
– Numbered from the largest chromosome to the
smallest
– Autosomes: chromosomes numbers 1-22
• Chromosomes contain genes for characteristics not
directly related to the sex of the organism
Your body cells have autosomes and
sex chromosomes
– Sex chromosomes: directly control the
development of sexual characteristics
• All mammals are based on the X and Y system
• This is the 23rd pair of chromosomes
• X and Y are paired together but they are not
homologous
– X chromosome is larger, contains many genes, even some
unrelated to sexual characteristics
– Y chromosome is smallest, carries fewest genes, contains
genes in direct development of male traits
Body cells are diploid, Gametes are
haploid
• Sexual Reproduction: fusion of two gametes
which results in the production of offspring that
are a genetic mixture of both parents
– Fertilization: actual fusion of egg and sperm
• Diploid: a cell has two copies of each
chromosome
–
–
–
–
One from mother, one from father
2n
In humans, diploid number is 46
***What would the haploid number be?****
Body cells are diploid, Gametes are
haploid
• Haploid: a cell has only one copy of each
chromosome
–n
– Human gametes
• Maintaining the correct number of chromosomes
is important to the survival of all organisms
– Typically change in number is harmful, but on
occasion increasing number of sets can give rise to
new species
Warm up (3-1-16)
Explain Mendel’s experiments in your own
words. Explain why his work was important.
Outline
•
•
•
•
•
•
Objectives
Mendel and Heredity
Notes 6.3
Read 6.4
Notes 6.4
Intro 6.5
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
Meiosis
• A form of nuclear division that divides a
diploid cell into haploid cells
– Essential for sexual reproduction
• Occurs in germ cells to produce gametes
• “reduction division” – reduce chromosome
number by half
• DNA is copied once but divided twice
• Genetically unique haploid cells form from a
diploid cell
Process of Meiosis
Meiosis Video
• https://www.khanacademy.org/science/biolog
y/cellular-molecular-biology/new-topic-201406-18T18:00:45.081Z/v/phases-of-meiosis
• https://www.youtube.com/watch?v=16enC38
5R0w
Meiosis I
Prophase I
Metaphase I
Anaphase I
Telophase I
Cytokinesis
Meiosis II
Prophase II
Metaphase II
Anaphase II
Telophase II
Cytokinesis
Meiosis Drawings and Notes on the
Phases
• Take a few minutes and use your paper to
draw the phases of meiosis.
• You may use the book if you need to
• We will be taking notes on the lines next to
the drawings so please try to keep your
drawings small enough to not cover the lines.
Warm up (3-2-16)
What is the law of segregation?
What are traits, genes, and alleles?
Use these terms and explain how each of these
terms is involved in genetics.
Outline
•
•
•
•
Objectives
6.5 Notes
Punnett Square practice - Bunny game
Chapter 6.1-6.3 Quiz
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
Meiosis
• A form of nuclear division that divides a
diploid cell into haploid cells
– Essential for sexual reproduction
• Occurs in germ cells to produce gametes
• “reduction division” – reduce chromosome
number by half
• DNA is copied once but divided twice
• Genetically unique haploid cells form from a
diploid cell
Meiosis Video
• https://www.khanacademy.org/science/biolog
y/cellular-molecular-biology/new-topic-201406-18T18:00:45.081Z/v/phases-of-meiosis
• https://www.youtube.com/watch?v=16enC38
5R0w
6.3 Notes - Mendel and Heredity
• Mendel’s research showed that traits are
inherited as discrete units
– Mendel laid the groundwork for genetics
• Traits: distinguishing characteristics that are inherited
• Genetics: study of biological inheritance
– Mendel’s Data revealed patterns of inheritance
• Purebred: genetically uniform
• Mendel chose 7 traits to look at
– Mendel controlled pollination by removing stamens
KEY CONCEPT
Mendel’s research showed that traits are inherited as
discrete units.
Mendel laid the groundwork for
genetics.
• Traits are distinguishing
characteristics that are
inherited.
• Genetics is the study of
biological inheritance
patterns and variation.
• Gregor Mendel showed that
traits are inherited as
discrete units.
• Many in Mendel’s day
thought traits were blended.
Warm up (3-3-16)
Perform the following cross by using a Punnett
Square: BB x Bb
Outline
• Objectives
• I do - we do - you do Punnett Square practice
• Punnett Square worksheet
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
Mendel’s data revealed patterns of
inheritance.
• Mendel made three key decisions in his experiments.
– use of purebred plants
– control over breeding
– observation of seven
“either-or” traits
• Mendel used pollen to fertilize selected pea plants.
– P generation crossed to produce F1 generation
– interrupted the self-pollination process by removing male
flower parts
Mendel controlled the
fertilization of his pea plants
by removing the male parts,
or stamens.
He then fertilized the female
part, or pistil, with pollen from
a different pea plant.
• Mendel allowed the resulting plants to self-pollinate.
– Among the F1 generation, all plants had purple flowers
– F1 plants are all heterozygous
– Among the F2 generation, some plants had purple
flowers and some had white
• Mendel observed patterns in the first and second
generations of his crosses.
• Mendel drew three important conclusions.
– Traits are inherited as discrete units.
– Organisms inherit two copies of each gene, one from
each parent.
– The two copies segregate
during gamete formation.
– The last two conclusions are
called the law of segregation.
purple
white
Warm up (3-4-16)
Explain the process of using a Punnett Square.
Can a Punnett Square be larger than 4 squares?
If so, explain how.
Outline
•
•
•
•
Objectives
Reading Ch. 6.6
Notes 6.5 (?) and 6.6
Chapter 6 Quizzes
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
6.4 Notes
KEY CONCEPT
Genes encode proteins that produce a diverse range
of traits.
The same gene can have many versions.
• A gene is a piece of DNA that directs a cell to make a
certain protein.
• Each gene has a locus, a
specific position on a pair of
homologous chromosomes.
• An allele is any alternative form of a gene occurring at a
specific locus on a chromosome.
– Each parent donates
one allele for every
gene.
– Homozygous
describes two alleles
that are the same at a
specific locus.
– Heterozygous
describes two alleles
that are different at a
specific locus.
Genes influence the development of
traits.
• All of an organism’s genetic material is called the genome.
• A genotype refers to the makeup of a specific set of genes.
• A phenotype is the physical expression of a trait.
• Alleles can be represented using letters.
– A dominant allele is
expressed as a phenotype
when at least one allele is
dominant.
– A recessive allele is
expressed as a phenotype
only when two copies are
present.
– Dominant alleles are
represented by uppercase
letters; recessive alleles by
lowercase letters.
• Both homozygous dominant and heterozygous genotypes
yield a dominant phenotype.
• Most traits occur in a range
and do not follow simple
dominant-recessive patterns.
Warm up (3-7-16)
Explain what crossing over is and which stage of
meiosis this process occurs in.
Outline
• Objectives
• 6.6 Reading and Notes
• Make a “baby” genetics project
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
Warm up (3-8-16)
Explain what causes traits to be passed down to
offspring from the parents. (Use the words,
traits, alleles, dominant, recessive,
heterozygous, and homozygous in your answer.)
Outline
• Objectives
• Genetics Project – Offspring Creation
• Mini partner quiz
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
Warm up (3-9-16)
Explain how phenotype is determined for
genetic crosses. (Don’t forget to mention which
alleles must be present for specific phenotypes
to appear.)
Outline
• Objectives
• Chapter 7 Intro
Objectives
• Describe how sexual reproduction creates
unique gene combinations
• Explain how crossing over during meiosis
increases genetic diversity
Video: Genetics and Heredity
• https://www.youtube.com/watch?v=NWqgZU
nJdAY
Warm up (3-10-16)
What does it mean if there is codominance for a
particular gene?
Outline
•
•
•
•
•
Objectives
Genetics video
Quick lab p. 185
Allele Combinations p. 188
Bunny Game!
Objectives
• Describe how sexual reproduction creates
unique gene combinations
• Explain how crossing over during meiosis
increases genetic diversity
Punnett Square Practice
• Composition notebooks to the next page.
• P. 185 in your books – Quick Lab
• P. 188 in your books – Allele combinations and
Punnett Squares
Punnett Square Practice
• Bunny Game
• http://vital.cs.ohiou.edu/steamwebsite/downl
oads/FurryFamily.swf
I do - We do - You do
• Punnett Square Practice
Punnett Square Worksheet
Warm up (3-14-16)
Explain how sexual reproduction generates new
allele combinations in offspring.
Outline
• Objectives
• Bunny Game!
• 6.5 and 6.6 Notes
Objectives
• Describe how sexual reproduction creates
unique gene combinations
• Explain how crossing over during meiosis
increases genetic diversity
6.5 Notes
KEY CONCEPT
The inheritance of traits follows the rules of
probability.
Punnett squares illustrate genetic
crosses.
• The Punnett square is a grid system for predicting all
possible genotypes resulting from a cross.
– The axes represent
the possible gametes
of each parent.
– The boxes show the
possible genotypes
of the offspring.
• The Punnett square
yields the ratio of
possible genotypes and
phenotypes.
A monohybrid cross involves one trait.
• Monohybrid crosses examine the inheritance of
only one specific trait.
– homozygous dominant-homozygous recessive: all
heterozygous, all dominant
– heterozygous-heterozygous—1:2:1 homozygous
dominant: heterozygous:homozygous recessive; 3:1
dominant:recessive
• heterozygous-homozygous recessive—1:1
heterozygous:homozygous recessive; 1:1
dominant:recessive
• A testcross is a cross between an organism with an
unknown genotype and an organism with the recessive
phenotype.
A dihybrid cross involves two traits.
• Mendel’s dihybrid crosses with heterozygous plants
yielded a 9:3:3:1 phenotypic ratio.
• Mendel’s dihybrid crosses
led to his second law,
the law of independent
assortment.
• The law of independent
assortment states that
allele pairs separate
independently of each
other during meiosis.
Heredity patterns can be calculated with
probability.
• Probability is the likelihood that something will happen.
• Probability predicts an average number of occurrences,
not an exact number of occurrences.
• Probability =
number of ways a specific event can occur
number of total possible outcomes
• Probability applies to
random events such as
meiosis and fertilization.
6.6 Notes
KEY CONCEPT
Independent assortment and crossing over during
meiosis result in genetic diversity.
Sexual reproduction creates unique
combinations of genes.
• Sexual reproduction creates unique combination of genes.
– independent assortment of chromosomes in meiosis
– random fertilization of gametes
• Unique phenotypes may give a reproductive advantage to
some organisms.
Crossing over during meiosis increases
genetic diversity.
• Crossing over is the exchange of chromosome
segments between homologous chromosomes.
– occurs during prophase I of meiosis I
– results in new combinations of genes
• Chromosomes contain many genes.
– The farther apart two genes are located on a
chromosome, the more likely they are to be separated
by crossing over.
– Genes located close together on a chromosome tend to
be inherited together, which is called genetic linkage.
• Genetic linkage allows the distance between two genes to
be calculated.
Genetics Project – Offspring Creation
• Chromosomes contain many genes.
– The farther apart two genes are located on a
chromosome, the more likely they are to be separated
by crossing over.
– Genes located close together on a chromosome tend to
be inherited together, which is called genetic linkage.
• Genetic linkage allows the distance between two genes to
be calculated.
Mini Quiz
• Complete the following crosses using simple
Punnett Squares
– BB x Bb
– Yy x yy
– Hh x Hh
• Find the percentage of dominant phenotypes for
each of the crosses
• Find the percentage of recessive phenotypes for
each of the crosses
• Now, use the following table to help identify the
phenotypes of the offspring.
Flower color
Fruit Color
Plant Height
DOMINANT
Blue (B)
Yellow (Y)
Tall (H)
RECESSIVE
White (b)
Green (y)
Short (h)
Warm up (3-15-16)
Describe how sex-linked genes are expressed
differently in males and females.
Outline
•
•
•
•
Objectives
Read ch. 7.1
Notes ch. 7.1
Sex linked inheritance p. 202
Objectives
• Describe how sexual reproduction creates
unique gene combinations
• Explain how crossing over during meiosis
increases genetic diversity
Extending Mendelian Genetics
7.1 KEY CONCEPT
The chromosomes on which genes are located can
affect the expression of traits.
Two copies of each autosomal gene affect
phenotype.
• Mendel studied autosomal
gene traits, like hair texture.
• Mendel’s rules of inheritance apply to autosomal
genetic disorders.
– A heterozygote for a recessive disorder is a carrier.
– Disorders caused by dominant alleles are uncommon.
(dominant)
Males and females can differ in sexlinked traits.
• Genes on sex chromosomes are called sex-linked genes.
– Y chromosome genes in mammals are responsible for male
characteristics.
– X chromosome genes in mammals affect many traits.
• Male mammals have an XY genotype.
– All of a male’s sexlinked genes are
expressed.
– Males have no
second copies of
sex-linked genes.
• Female mammals have an XX genotype.
– Expression of sex-linked genes is similar to autosomal
genes in females.
– X chromosome inactivation randomly “turns off” one X
chromosome.
Sex – Linked Inheritance
• P. 202
• Problem – How does probability explain sexlinked inheritance
– Answer this question as your prediction
• Procedure – follow the procedure on page 202
• When you finish the procedure, answer the
analysis and conclusion questions in your
composition notebook using complete
sentences.
Warm up (3-16-16)
Explain what happens during fertilization.
(Include the terms – gametes, diploid and
haploid in your answer)
Outline
• Objectives
• Sex linked inheritance p. 202
Objectives
• Describe how sexual reproduction creates
unique gene combinations
• Explain how crossing over during meiosis
increases genetic diversity
Sex – Linked Inheritance
• P. 202
• Problem – How does probability explain sexlinked inheritance
– Answer this question as your prediction
• Procedure – follow the procedure on page 202
• When you finish the procedure, answer the
analysis and conclusion questions in your
composition notebook using complete
sentences.
7.2 KEY CONCEPT
Phenotype is affected by many different factors.
Phenotype can depend on interactions of
alleles.
• In incomplete dominance, neither allele is
completely dominant nor completely recessive.
– Heterozygous phenotype is intermediate between
the two homozygous phenotypes
– Homozygous parental phenotypes not seen in F1
offspring
• Codominant alleles will both be completely expressed.
– Codominant
alleles are
neither
dominant nor
recessive.
– The ABO blood
types result
from
codominant
alleles.
• Many genes have more than two alleles.
Many genes may interact to produce one
trait.
• Polygenic traits are
produced by two or
more genes.
Order of dominance:
brown > green > blue.
• An epistatic gene can interfere with other genes.
The environment interacts with
genotype.
• Phenotype is a combination
of genotype and
environment.
• The sex of sea turtles
depends on both genes
and the environment
• Height is an example of a
phenotype strongly affected
by the environment.
Warm up (3-17-16)
Explain what codominance is and give an
example of a codominant trait.
Outline
•
•
•
•
Objectives
Codominance p.208
Read 7.3
Notes 7.3
Objectives
• Explore codominance by investigating the
inheritance of sickle cell disease within a
family
• Infer genotypes using knowledge of
heterozygous and homozygous alleles
• Use punnett squares to predict patterns of
gene inheritance and gene expression
p. 208 Codominance
• Read through the background information
about sickle cell disease. Then follow the
procedure to answer the 5 questions in your
composition notebook. Please use complete
sentences while working on this.
7.3 KEY CONCEPT
Genes can be mapped to specific locations on
chromosomes.
Gene linkage was explained through fruit
flies.
• Morgan found that linked traits are on the same
chromosome.
• Chromosomes, not genes, assort independently during
meiosis.
Wild type
Mutant
• Linked genes are not inherited together every time.
• Chromosomes exchange homologous genes during
meiosis.
Linkage maps estimate distances
between genes.
• The closer together two genes are, the more likely
they will be inherited together.
• Cross-over frequencies are related to distances
between genes.
• Linkage maps show the relative locations of genes.
• Cross-over frequencies can be converted into map units.
– gene A and gene B cross over 6.0 percent of
the time
– gene B and gene C cross over
12.5 percent of the time
– gene A and gene C cross over 18.5 percent of the time
Warm up (3-21-16)
Outline
• Objectives
Objectives
7.4 KEY CONCEPT
A combination of methods is used to study human
genetics.
Human genetics follows the patterns
seen in other organisms.
• The basic principles of genetics are the same in all
sexually reproducing organisms.
– Inheritance of many human
traits is complex.
– Single-gene traits are
important in understanding
human genetics.
Females can carry sex-linked genetic
disorders.
• Males (XY) express all of their sex linked genes.
• Expression of the disorder depends on which parent
carries the allele and the sex of the child.
Y
X
A pedigree is a chart for tracing genes in
a family.
• Phenotypes are used to infer genotypes on a pedigree.
• Autosomal genes show different patterns on a pedigree
than sex-linked genes.
• If the phenotype is more common in males, the gene is
likely sex-linked.
Several methods help map human
chromosomes.
• A karyotype is a picture of all chromosomes in a cell.
XY
• Karyotypes can show changes in chromosomes.
– deletion of part of a chromosome or loss of a
chromosome
– large changes in chromosomes
– extra chromosomes or duplication of part of a
chromosome
Blood Smears
Warm up (3-27-15)
Explain how particular traits can be polygenic
traits. Provide an example of polygenic traits.
Outline
• Objectives
• Chapter 7 quizzes
• Take home test for homework
Objectives
• Students will be able to identify the difference
between sex cells and somatic cells and
explain why these two types of cells are
different.
• Students will be able to identify the steps in
meiosis and explain what is occurring to the
chromosomes at each step
Blood Typing
Chapter 6-7 Quiz
Blood Typing
• http://www.redcrossblood.org/learn-aboutblood/blood-types